AN EXPERIMENTAL STUDY OF PRESERVATION POTENTIALS OF SOFT-BODIED ORGANISMS ON SAN SALVADOR, BAHAMAS

Unlike organisms with biomineralized skeletal parts, soft-bodied remains are less likely to be preserved in the fossil record. Much work has been done to better understand the pathways that may lead to preservation of soft-bodied organisms. The purpose of this decay study was to catalog necrolysis stages of both diploblastic and triploblastic organisms, the cnidarian Condylactis gigantea and the feather duster polychaete Bispira brunnea respectively, utilizing a semi-quantitative experimental approach. Four anatomical features shared by the two organisms were evaluated as decay progressed to allow for comparison. A total of 20 specimens of C. gigantea and 20 specimens of B. brunnea, freshly euthanized, were deployed in small chambers on subtropical San Salvador Island, The Bahamas, in three settings: (1) Storr’s Lake, a hypersaline, microbial mat dominated community; (2) Graham’s Harbor, an oxygenated shallow subtidal seafloor; and (3) a controlled saltwater aquarium. Decay progressed at a substantially slower pace for specimens deployed within the hypersaline, microbial setting when comparing with the subtidal marine environment and laboratory settings. Typically B. brunnea scored lower total body decay values than C. gigantea. An additional sample of 10 C. gigantea were deployed into the hypersaline, microbial mat dominated Storr’s Lake after incisions had been made exposing internal anatomy of all deployed specimens to external environmental factors. The injuries further increased reduction in the rate of decay, prolonging the amount of time for which the recognizable features of the sea anemones persisted. This study documents necrolysis stages of sea anemones and feather duster polychaetes and indicates that injury may slow down a decay process and thus enhance preservation potential of soft-bodied organisms.